Internal combustion engine and electric motor powered vegetation trimmers are commonly used to cut and trim grass, weeds, brush and other vegetation. The typical motorized trimmer comprises an elongate handle to which is connected an internal combustion or electric motor that rotatably drives a trimmer head located at a distal end of the handle. The trimmer head, in turn, carries radially outwardly projecting cutting means which cuts the vegetation as the trimmer head rotates.
The trimmer head may include one or more flexible or rigid cutting means. If rigid, the cutting means typically assumes the form of blades fabricated from plastic and/or metal and often have corrugations or scalloping about their peripheral cutting edges. The blades are pivotally attached to the trimmer head such they yield when they contact hard objects, thereby prolonging the service lives of the blades. Rigid blades are normally used to cut very dense vegetation but they may cause considerable injury to the trimmer operator or other persons should they accidentally be struck by the blades during operation of the trimmer.
If flexible, the cutting means may be fabricated as a continuous strand flexible monofilament plastic line wrapped about a spool contained within the trimmer head. In such devices, the plastic line is typically selectively dispensed by the operator of the trimmer apparatus. One species of these sorts of devices is semi-automatic in operation and utilizes the centrifugal force generated by rotation of the trimmer head to dispense trimmer line. Commonly known as “bump indexing” or “bump and feed” trimmers, these apparatus dispense trimmer line responsive to an operator tapping the base of the trimmer head against a hard surface. An example of bump indexing trimmer head is shown in U.S. Pat. No. 6,279,235.
A disadvantage common among bump and feed trimmers is that the trimmer line frequently becomes jammed when a user attempts to dispense fresh line from the spool. When this occurs, the user must stop the trimming operation, disassemble the trimmer head, fix the jam and reassemble the trimmer head before resuming trimming. Such repeated disruption can be quite frustrating and time-consuming.
Another species of vegetation trimmer apparatus where trimmer line is selectively dispensed from a spool by an operator is fully manual in operation. Devices of this sort comprise one or more, typically spring-biased, indexing pins or buttons that are connected to one or more internal trimmer line carrying spools. In order to dispense trimmer line, an operator displaces the indexing pin(s) or button(s) from seating engagement with one or more holes provided in the trimmer head housing. Once the indexing pin(s) or button(s) are separated from the housing, the user either turns the internal spool(s) or pulls on the trimmer line itself from the spool in order to pay out the line from the trimmer head. When the desired length(s) of trimmer line have been dispensed, the operator reseats the indexing pin(s) or button(s) into their associated indexing opening(s) in the trimmer head housing.
The trimmer line dispensing steps required of conventional fully manual trimmer heads are often cumbersome to perform with two hands. The trimmers are also complicated in design which needlessly increases their manufacturing costs. Examples of various designs of fully manual trimmer line trimmer heads are disclosed in U.S. Pat. Nos. 4,271,595; 4,172,322; 4,097,991; 3,826,068 and 3,708,967.
In addition to trimmer line dispensing problems, presently available semi-automatic and fully manual trimmer heads are often difficult to reload with fresh trimmer line when their spools have been depleted. Once the new trimmer line has been wrapped around the spool, the installer must grasp the trimmer head housing while holding the line in the wrapped position about the spool and then insert the spool into the housing. This procedure is especially cumbersome with respect to bump indexing trimmers because the installer must also hold and/or maintain alignment of any springs or other loose components of the bump and feed indexing system during the spool installation process.
Attempts to overcome these problems have been proposed in the prior art. For example, U.S. Pat. Nos. 5,671,536 and 6,263,580 disclose spool reloading solutions for bump and feed trimmers wherein trimmer line can be wound onto the internal spool without removing the spool from the trimmer head housing, although the system taught by U.S. Pat. No. 5,671,536 requires additional user participation to anchor the trimmer line to the spool prior to winding/loading it on the spool. However, the results are trimmer line spools of highly complex configuration whose manufacturing costs are unnecessarily expensive.
U.S. Pat. No. 5,765,287 also describes a trimmer head that enables winding of a desired quantity of trimmer line on a spool without removing the spool from the trimmer housing. In one embodiment, the device incorporates a rigid trimmer line guide tube that spans most of the diameter of the spool. Trimmer line is threaded into one trimmer line exit port in the trimmer head housing and passed through the guide tube. Upon exiting the guide tube the trimmer line is passed through the opposite trimmer head housing exit port. When the desired length of trimmer line is threaded through the trimmer head, the installer rotates a knob integrally connected to the spool and the trimmer line is wound onto the core of the spool.
The trimmer head disclosed in U.S. Pat. No. 5,765,287 suffers certain disadvantages, however. That is, the rigid trimmer line guide tube presents an obstruction in the spool chamber that hinders uniform and compact winding of the trimmer line onto the spool. Additionally, the trimmer line can also be damaged or severed as it comes into contact slotted edges at the opposite ends of the guide tube during winding.
An advantage exists, therefore, for a vegetation trimmer apparatus including a rotatable trimmer head that incorporates trimmer line indexing means and coil winding means of simple, economical and reliable design, construction and operation.
Other details, objects and advantages of the present invention will become apparent as the following description of the presently preferred embodiments and presently preferred methods of practicing the invention proceeds.